Cancer therapies kill cancer cells, but are only marginally less toxic to healthy cells. We need more selective agents to specifically kill cancer cells. Since cancer cells divide so rapidly, they are very often hypoxic (oxygen-starved). This hypoxia can be used to specifically target cancer cells for destruction. The long-term goal of this research is to develop new hypoxia-targeting anticancer drugs that are less toxic, more selective, and more potent. The objective of this particular application is to design and synthesize a series of new radiation-activated antitumor agents that contain dual potent effectors and more efficient triggers, and to perform biological studies with both synthetic and cellular DNA. These agents should be non-toxic in normal tissue, and can be selectively activated to release multiple toxic species (effectors) upon irradiation under the hypoxic conditions found in tumor tissue. The effectors are designed to form deleterious DNA damage, such as DNA interstrand cross-links (ICLs) or DNA alkylations that can block DNA replication or transcription and kill tumor cells. The proposed research has been formulated on the basis of our recent discovery that the arylmethyl radicals form the DNA interstrand crosslinks under hypoxic condition. The rationale for the proposed research is that, once the efficient triggers and the potent effectors are developed, the new agents will be more selective and more potent anticancer drug candidates for the treatment of aggressive cancers. Synthetic methodologies will be developed to prepare the proposed compounds. They will be incorporated into short oligonucleotides via solid- phase DNA synthesis. Their DNA-damage profiles and mechanism with respect to cross-link formation and DNA alkylation will be studied. The hypoxia-specificity will be evaluated by examining cross-linking efficiency under hypoxic or aerobic conditions. The most promising agents will be pushed forward for in vitro and in vivo study with tumor cells. In addition, new, potent DNA- damaging functional groups will be prepared, as well as other analogs. The knowledge gained from this study will be useful for addressing fundamental questions concerning DNA damage and anticancer drug development and will benefit a broad range of disciplines, including organic chemistry, biochemistry, medicinal chemistry, toxicology, and cell biology. PUBLIC HEALTH RELEVANCE: The proposed research is relevant to public health because the development of new hypoxia- targeting antitumor agents has the potential to identify a new class of anticancer drugs for the treatment of aggressive cancers. The knowledge acquired will be useful for addressing fundamental questions concerning DNA damage and anticancer drug development. Thus, the proposed research is relevant to the part of NIH's mission that is in pursuit of fundamental knowledge that will help to reduce the burdens of human illness.